Login to Access Video or Poster Abstract: MP82-11
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Introduction

We investigate the relationship between circadian rhythm and water metabolism and expression of circadian clock gene in peripheral bladder and central micturition centers.

Methods

Normal mouse (C57BL/6J male; WT) and circadian gene knock-out mouse (per1-/-per2-/-; PDK) was used. Water intake and urine output according to the circadian rhythm was checked using metabolic cage in 12:12 LD photoperiodic cycle (LD cycle) and constant dark cycle (DD cycle) in both WT and PDK. Circadian clock gene expression rhythm in bladder was evaluated with the activation of Per2 promotor. Circadian expression of representative clock gene was analysed; Bmal1 and Rev-erb? and rhythmic expression of circadian clock gene was analysed according to time in three main functional tissue related with micturition (detrusor smooth muscle, sphincter smooth muscle and urothelium) in both WT and PDK. Expression of clock gene in central micturition center was analysed; lumbar spinal cord, pontine micturition center (PMC) and ventrolateral periaqueductal gray (vlPAG), real-time RT-PCR was used in every 3 hours for 24 hours in DD cycle in both WT and PDK.

Results

Water intake and urine output was increased in night-time of WT in LD and DD cycle. However this tendency was disappeared to PDK. Water intake and urine output was increased in night-time of WT in LD cycle and DD cycle was disappeared in PDK and this means that circadian rhythm is due to endogenous circadian rhythm not outside environment. We can observe the activation of Per2 promotor approximately 24 hours of rhythm. And this finding represents that bladder peripheral clock was well functioned. In case of WT, characteristic circadian expression pattern of clock gene in all three tissues. On the contrary, 24 hours of promoter activated rhythm was not observed in PDK. In spinal level, unlike PDK, clock gene expression rhythm was observed in WT. But, there was no definite rhythmicity of circadian expression pattern of clock gene in the upper region of central micturition center like PMC and vlPAG.

Conclusions

Endogenous circadian rhythm in water intake and urine output is exist approximately 24 hours. Bladder peripheral clock gene is existed in main functional tissue related with micturition. But in terms of central micturition center, we can find circadian clock gene expression only in lumbar spinal cord. Further study about the reason why absence of circadian clock in upper central micturition center and finding other circadian control mechanism in upper micturition center is needed.

Funding

none